The present invention relates to an analyzing method for analyzing minute foreign substances existing on the surface of a planar sample such as a silicon wafer for use in manufacture of a semiconductor device, an insulative transparent substrate for use in manufacture of a liquid crystal display device, etc., an analyzing apparatus therefor, and a manufacturing method for manufacturing a semiconductor device or liquid crystal display device by using the analyzing method and analyzing apparatus. More particularly, the invention relates to a method and apparatus for, concerning a minute foreign substance having beedetected and having had its position particularized by a particle examination equipment whose equipment coordinates are defined beforehand, enabling easy analysis, examination and evaluation of the particularized minute foreign substance by linking the particularized existing position of the minute foreign substance with the coordinates of an analyzing apparatus, and a manufacturing method for manufacturing a semiconductor device and liquid crystal display device by using these method and apparatus.
Note the following. The analyzing apparatus referred to here in this specification is defined to mean an analyzing apparatus which irradiates energy of various corpuscular rays such as light, x rays, electromagnetic waves, electrons, neutral chemical species (atoms, molecules, etc.), ions or phonons onto the surface of a sample and detects secondary corpuscular rays absorbed or radiated due to interaction thereof with the sample to thereby examine the color tone, cubic image, elemental analysis, chemical structure, crystalline structure and the like of the surface of the sample or process this sample surface. For example, it includes apparatuses having the analyzing, examining, evaluating, and/or processing function such as, for example, metallurgical microscopes, laser microscopes, probe microscopes, interatomic force microscopes (hereinafter referred to as "AFM"), scanning tunnel microscopes (hereinafter referred to as "STM"), magnetic force microscopes (hereinafter referred to as "MFM"), scanning electron microscopes (Scanning Electron Microscope, hereinafter referred to as "SEM"), electron probe micro-analyzers (Electron Probe Micro-Analyzers, hereinafter referred to as "EPMA"), x-ray photoelectron spectrometers (X-ray Photoelectron Spectrometer, hereinafter referred to as "XPS"), ultraviolet photoelectron spectrometers (Ultraviolet Photoelectron Spectrometer, hereinafter referred to as "UPS"), secondary ion mass spectrometers (Secondary Ion Mass Spectrometer, hereinafter referred to as "SIMS"), time of flight-SIMSes (Time Of Flight-SIMS, hereinafter referred to as "TOF-SIMS"), scanning Auger electron spectrometers (Scanning Auger Electron Spectrometer, hereinafter referred to as "SAM"), Auger electron spectrometers (Auger Electron Spectrometer, hereinafter referred to as "AES"), reflection high energy electron diffraction spectrometers (Reflection High Energy Electron Diffraction Spectrometer, hereinafter referred to as "RHEED"), high energy electron diffraction spectrometers (High Energy Electron Diffraction Spectrometer, hereinafter referred to as "HEED"), low energy electron diffraction spectrometers (Low Energy Electron Diffraction Spectrometer, hereinafter referred to as "LEED"), electron energy-loss spectrometers (Electron Energy-Loss Spectrometer, hereinafter referred to as "EELS"), focused ion beam instruments (Focused Ion Beam Instruments, hereinafter referred to as "FIB"), particle induced X-ray emission spectrometers (Particle Induced X-Ray Emission, hereinafter referred to as "PIXE"), Microscopic Fourier transformation infrared-ray spectrometers (hereinafter referred to as "Microscopic FT-IR") or Microscopic Raman, observation apparatuses, analyzing apparatuses, examination apparatuses and evaluation apparatuses, having the above-mentioned functions.
It is said that inferior yield in the manufacture of ultrahigh LSIs represented by 4 M bit-DRAMs, 16 M bit-DRAMs and the like is for the most part attributable to defective wafers resulting from attachments on wafers.
The reason for this is that as the pattern width becomes micronized, a micro-size of foreign substances attached on wafers, which were conventionally not deemed as problematic, become contamination sources in preceding manufacturing process steps. Generally, it is said that the size of these problematic minute foreign substances is one of several of a minimum wiring width of an ultrahigh LSI to be manufactured. For this reason, in a 16 M bit-DRAM (minimum wiring width: 0.5 .mu.m), minute foreign substances having a diameter of 0.1 .mu.m or so are object foreign substances. These minute foreign substances become contamination substances which cause wiring breakage and shortcircuiting of the circuit patterns, which in turn largely causes generation of defective products and causes a decrease in the quality and reliability. Therefore, grasping the actual condition of minute foreign substances such as a state of attachment thereof through quantitative and precise measurement and analysis and conducting relevant managements are a key to increasing the yield.
As means for conducting the above-mentioned grasp and management, there is conventionally employed a particle examination equipment capable of detecting the positions of minute foreign substances existing on the surface of a planar sample such as a silicon wafer. Note that as the conventional particle examination equipments there are one produced by Hitachi Electron Engineering Limited and having an equipment name of IS-2000 and LS-6000, one produced by Tencor Corporation in the United States of America and having an equipment name of Surfscan 6200, one produced by Estek Corporation in the United States of America and having an equipment name of WIS-9000, and the like. Also, the measuring principles used in these particle examination equipments and the equipment constructions for realizing them are described in detail in, for example, a literature "High Performance Semiconductor Process Analysis and Evaluation Technology", pages 111 to 129, edited by Semiconductor Foundation Technology Study Association and published by Realize Ltd.
FIG. 9 illustrates a CRT display image screen which shows the results of measurements made on minute foreign substances (0.1 .mu.m or more) existing on an actual 6-inch silicon wafer by using the particle examination equipment LS-6000. Namely, this display image screen only shows rough positions of minute foreign substances, the number thereof per unit size thereof and particle size distribution thereof. The circle shown in FIG. 9 indicates the outer periphery of the 6-inch silicon wafer and the dots existing therewithin correspond to the positions where minute foreign substances exist. Note that the particles and foreign substances described here are defined to mean foreign or different portions as viewed with respect to a wafer, such as protrusions, depressions, attaching particles, defects and the like, namely foreign or different portions at which light scattering (irregular reflection) occurs.
However, as seen from FIG. 9, since data obtained from conventional particle examination equipments are only the sizes of minute foreign substances existing on the surface of a sample such as a silicon wafer and the existence positions thereof on the sample surface, the actual condition of such minute foreign substances such as what these substances are cannot be particularized.
For example, FIG. 5 is a view illustrating a fundamental construction of a conventional actuator-equipped metallurgical microscope such as an IC examination microscope apparatus MODER: IM-120 put on sale from Nidek Co.Ltd., which is an example of a metallurgical microscope having the positioning function used for detecting minute foreign substances. In FIG. 5, a silicon wafer 2 as a sample is placed on an x-y actuator 1 having coordinates which have been roughly linked with the coordinates of a particle examination equipment. It is arranged that a foreign substance 7 detected by the particle examination equipment is carried into a view field of the metallurgical microscope 3 or into therearound on the basis of position data of the foreign substance obtained from the particle examination equipment by means of an x-y actuator 1. The examination procedures used when the foreign substance 7 existing on the surface of a planar silicon wafer is examined using a conventional actuator-equipped metallurgical microscope and the results of the examination will now be described.
First, a plurality of somewhat stained and mirror surface-polished silicon wafers 2 (Mitsubishi Material Silicon-Produced CZ &lt;plane orientation: 100&gt;6-inch diameter silicon wafer) were applied onto a particle examination equipment (a particle examination equipment produced by the United States of America, Tencor Corporation and having an equipment name of Surfscan 6200) and the rough sizes and rough existence positions of foreign substances existing on each silicon wafer 2 were observed. On each silicon wafer 2 there existed at random positions about 800 foreign substances whose sizes were in a range of from 0.1 to 0.2 .mu.m in average, about 130 foreign substances whose sizes were in a range of from 0.2 to 0.3 .mu.m in average, about 30 foreign substances whose sizes were in a range of from 0.3 to 0.4 .mu.m in average, about 13 foreign substances whose sizes were in a range of from 0.4 to 0.5 .mu.m in average, and about 15 foreign substances whose sizes were 0.5 .mu.m or more. Note that the coordinates of the Surfscan 6200 are defined such that the direction of a straight line tangential to an orientation flat (hereinafter referred to as "an orientation flat") of the wafer is set to be an x coordinate axis (or y coordinate axis); the direction of a straight line perpendicular thereto within a wafer plane is set to be a y coordinate axis (or x coordinate axis); and three or more points on the outermost periphery of the wafer (however excluding the orientation flat portion) are measured and these points are applied to the equation of a circle or ellipse to thereby set the coordinates of the position of a center of the wafer to be (0, 0).
Next, using a conventional actuator-equipped metallurgical microscope, the direction of a straight line tangential to an orientation flat of the wafer is set to be an x coordinate axis; the direction of a straight line perpendicular thereto within a wafer plane is set to be a y coordinate axis (or x coordinate axis); and three or more points on the outermost periphery of the wafer (however excluding the orientation flat portion) are measured and these points are applied to the equation of a circle or ellipse to thereby set the coordinates of the position of a center of the wafer to be (0, 0). In this condition, the silicon wafer 2 was set on an x-y actuator 1 which, in turn, was moved according to the position data of the foreign substances obtained from the particle examination equipment. Thereafter, the foreign substances having their respective sizes were observed using the metallurgical microscope 3 (Note that the foreign substances were evaluated and observed with the ocular lens being set to fixed 20 magnifications and the objective lens being set to variable 5, 20 and 50 magnifications.)
As a result, in the case of using the metallurgical microscope with 5-magnification objective lens, it was only possible to observe foreign substances having a size of around 0.4 to 0.5 .mu.m as dark dots at most and foreign substances having a size smaller than this size were almost not observed. On the other hand, foreign substances having: a size of 0.4 .mu.m or more could all be observed. Meanwhile, in the case of using the 50-magnification objective lens, it was sometimes possible to observe foreign substances having a size of around 0.2 to 0.3 .mu.m as dark dots. However, foreign substances having a size smaller than this size were almost not observed. Therefore, in order to investigate causes thereof, the amount of divergence between the coordinates at this time was examined using a plurality of wafers formed with grated patterns. As a result, it was proved that in the x-y coordinate display the amount of divergence of (.+-.250 .mu.m, .+-.250 .mu.m) in approximation existed regarding the origin position or center position and a given point definable therein.
In contrast, whereas the view field of the apparatus with 5-magnification objective lens, used at this time, was approximately 1500 .mu.m.PHI., the view field of this apparatus with 50-magnification objective lens was only approximately 150 .mu.m.PHI..
Namely, it was proved that the reason why at a time of the 50-magnification objective lens most of foreign substances having a-size of around 0.2 to 0.3 .mu.m could not be found was that by changing the magnification of the objective lens from 5 magnifications to 50 magnifications the amount of divergence became larger than the range of the view field of the microscope, with the result that the object foreign substances having a size of around 0.2 to 0.3 .mu.m did not fall within the view field of the presently available apparatus.
Accordingly, it is necessary to identify the actual condition of each of the individual minute foreign substances by directly observing or making composition analysis of these substances byluse of a suitable analyzing apparatus such as SEM. However, since the existence positions of individual foreign substances on the wafer obtained from the particle examination equipment are defined in the equipment coordinates of the particle examination equipment, those existence positions as defined therein are not always in coincidence with those defined in the apparatus coordinates of an analyzing apparatus which is not a particle examination equipment. Also, when a sample such as a wafer having had their foreign substances examined by the particle examination equipment is set on an analyzing apparatus such as SEM which is not a particle examination equipment, it is inevitable that coordinate divergence errors attributable to such new setting occur. For this reason, in order to identify the actual condition of a minute foreign substance, it is necessary to link the equipment coordinates of the particle examination equipment with the apparatus coordinates of an analyzing apparatus such as SEM which is not a particle examination equipment with a high precision by use of some measures.
Therefore, examination was performed on the equipment and apparatus coordinates on respective x-y stages of individual particle examination equipments and analyzing apparatuses such as SEM which are not particle examination equipments. As a result, it was found out that the coordinates on each of the x-y stages adopted in almost all of the equipments and apparatuses were of an x-y coordinate system. Also, the following two methods are adopted as methods for determining the coordinate axes and the origin position of each equipment or apparatus with respect to a wafer as a sample: (1) the direction of a straight line tangential to an orientation flat of the wafer is set to be an x coordinate axis (or y coordinate axis); the direction of a straight line perpendicular thereto within a wafer plane is set to be a y coordinate axis (or x coordinate axis); and a point of intersection between the outermost periphery of the wafer and the y coordinate axis is set to be (0, y) and a point of intersection between the y coordinate axis and the x coordinate axis is set to be (0, 0) (see FIG. 10(a)), and (2) the direction of a straight line tangential to an orientation flat of the wafer is set to be an x coordinate axis (or y coordinate axis); the direction of a straight line perpendicular thereto within a wafer plane is set to be a y coordinate axis (or x coordinate axis); and three or more sampling points on the outermost periphery of the wafer are measured and these points are applied to the equation of a circle or ellipse to thereby set the coordinates of the position of a center of the wafer to be the origin (0, 0) (see FIG. 10 (b)).
However, in the above-mentioned methods, since the function used to define the coordinates or the number of sampling points differs according to the type of the equipments or apparatuses, the defined coordinate system also differs. Also, it is inevitable that the positions of sampling points become varying due to a difference in .surface precision between the orientation flats or the outermost peripheral portions of wafers, due to a delicate difference in size between wafers, due to a difference in precision between the settings of wafers on the sample stage, or due to delicate warpage of a wafer. For this reason, divergence inevitably occurs between wafers or settings thereof in respect of the coordinate axis and the origin or center position. As a result of this, in a case where there is used a simple "method for linking coordinates which consists of inputting the position data of minute defects or foreign substances detected by a particle examination equipment to the coordinates of an analyzing apparatus which is not a particle examination equipment", which method was conventionally used, it is inevitable that divergence occurs between the equipment and apparatus coordinates with respect to each wafer in respect of the coordinate axis and origin. As a result, even when the analyzing apparatus is set to a magnification capable of analyzing minute foreign substances, it becomes impossible to set minute defects or foreign substances within a view field of that analyzing apparatus. For this reason, using a plurality of wafers formed with grated patterns, various equipments and apparatuses were examined concerning the amounts of divergence between their coordinates occurring due to the above-mentioned causes. As a result, it has been proved that even between high precision equipment and apparatus (a particle examination equipment produced by Hitachi Electron Engineering Limited and having an equipment name of IS-2000 and a length-measuring SEM produced by Hitachi Limited and having an apparatus name of S-7000) an amount of divergence of approximately (.+-.100 .mu.m, .+-.100 .mu.m) occurs in the x-y coordinate display in respect of the origin position or center position and a given point definable therein. When it is desired to observe, analyze and evaluate a minute foreign substance at a given position on a wafer detected by a particle examination equipment by use of an analyzing apparatus such as SEM which is not a particle examination equipment, it becomes necessary to observe it at least within a range covering an area which spreads (.+-.100 .mu.m, .+-.100 .mu.m) or more from a position where the minute foreign substance detected by the particle examination equipment is considered to exist, taken as the center (200 .mu.m.times.200 .mu.m=40000 .mu.m , the view field of SEM having 500 magnifications), by use of an analyzing apparatus such as SEM which is not a particle examination equipment and thereby confirm the position of it, and then conduct observation, analysis and evaluation thereof which are the initial goal by some suitable method such as by enlargement thereof. This requires the use of a significantly long period of time.
On the assumption that in order to intuitionally grasp of what size this range is with respect to a minute foreign substance this range of 40000 .mu.m.sup.2 (200 .mu.m.times.200 .mu.m) has been observed using a 1-million pixel CCD camera presently considered as a CCD camera having a relatively high resolving power, the minimum size of a minute foreign substance considered as being detectable attempts to be considered by calculating a detection range (area) occupied by one pixel of this CCD camera. The detection range occupied by one pixel under the above-mentioned conditions is calculated to be 0.04 .mu.m.sup.2 (4 million .mu.m.sup.2.div.1 million=0.2 .mu.m.times.0.2 .mu.m). On the other hand, since a substance having a size smaller than the size corresponding to the one-pixel detection range is difficult to discriminate, the minimum detectable size of a minute foreign substance is 0.04 .mu.m.sup.2 (0.2 .mu.m.times.0.2 .mu.m). Namely, it is difficult to detect a minute foreign substance whose projection area is smaller than 0.04 .mu.m.sup.2 (the diameter: 0.2 .mu.m) by directly using a 1-million pixel CCD camera. It is also seen that it is very difficult to particularize the position of the minute foreign substance. To say furthermore, it is almost impossible to particularize the position of a minute foreign substance having a size of 0.2 .mu.m or less.
For the above-mentioned reasons, in the prior art, it is generally difficult to particularize the position of a minute foreign substance with a diameter of 0.2 .mu.m or less detected by a particle examination equipment and directly observe or evaluate the minute foreign substance, by causing linkage between the equipment coordinates of the particle examination equipment and the apparatus coordinates of an analyzing apparatus such as SEM which is not a particle examination equipment.
Meanwhile, in order to cause the place where a foreign substance exists within a wafer to be interrelated between a foreign substance examination equipment and an analyzing apparatus, interface means is provided for storing and communizing position coordinate data of a detected minute foreign substance and also making file conversion and coordinate transformation. Then, the communized position coordinate data are used in each of the equipment and apparatus to thereby correct positional divergence between the equipment and the apparatus. This method of correcting is disclosed in Unexamined Japanese Patent Publication No. H-4-123454. Also, Unexamined Japanese Patent Publication No. H-3-102845 discloses a method of setting a coordinate system used as a standard with respect to wafers, providing each examination equipment with a conversion section for making conversion between the standard coordinate system and a coordinate system specific for the examination equipment, and inputting and outputting the coordinates totally in accordance with the standard coordinate system, or setting the coordinate system of each equipment totally in accordance with the standard coordinate system. However, in any one of these methods, a coordinate system specific for each equipment or a standard coordinate system is defined using a scribe line on a wafer or, for example, one leftmost point of a wafer periphery as a standard. Therefore, the resulting coordinate axis per se diverges due to the detection precision of the scribe line or orientation flat of a wafer or the leftmost point of a wafer periphery (which largely differs if the direction of the x coordinate axis is inclined even a little bit) and therefore is not an invariable coordinate axis. For this reason, it is inevitable that coordinate axis divergences occur between the equipments and apparatuses.